A well-known process for the production of acetic anhydride from acetic acid involves the formation of ketene (ethenone). Thereby ketene is produced by dehydrating acetic acid at high temperatures (typically in a ketene furnace operated at temperatures of the order of 700° C. to 750° C.). Subsequently, the ketene is reacted with acetic acid in an exothermic reaction leading to the formation of acetic anhydride.
Interestingly, both acetic acid and acetic anhydride are used in processes for the acetylation of wood. These processes, for which there is an increasing demand, serve to provide the wood with improved material properties, e.g. dimensional stability, hardness, durability, etc. In these processes, excess acetylation medium, typically a mixture of acetic anhydride and acetic acid, is ultimately removed from the wood. It is thereby desired to avoid wasting the removed acetylation medium, and preferably to recirculate and re-use it in wood acetylation.
It is desired to provide a method by which the acetylation of wood and the production of acetic anhydride can be effectively integrated, preferably with reduced equipment and operational expenses. Also, it is desired to thereby make optimal use of sources of liquid as available from wood acetylation.